Materials and products made therefrom must exhibit resistance to degradation if they are to be successfully marketed. Degradation can be seen as a partial or total loss of structural integrity, a darkening or discoloration of the product, a loss of flexibility or resilience, or a combination of the above phenomena. These phenomena are promoted or catalyzed by air (oxygen), heat, and light, particularly ultraviolet light.
To protect materials, ingredients which can be collectively called stabilizers are admixed with the materials to prevent or inhibit degradation. These stabilizers work in diverse and complex ways, such that a compound which stabilizes against heat and oxygen degradation in a material may not stabilize against light degradation in the same material, or vice versa. Furthermore, a compound which acts as a stabilizer against oxygen degradation in one type of material may be relatively inactive in another type of material. Thus, compounds which are stabilizers are further classed as antioxidants, antiozonants, heat stabilizers, and ultraviolet (UV) light stabilizers, depending upon what type of activity and stabilization they demonstrate. In many cases, to obtain optimum protection, a mixture of compounds, each specifically selected to afford maximum protection against a certain type of degradation, is often used.
The present invention is directed to a new class of UV stabilizers. The basic structure of this class is a nitrogen-substituted decahydroquinoline, exemplified in its simplest form as 1,2,2,4-tetramethyldecahydroquinoline. Other art in this area is as follows: U.S. Pat. Nos. 3,362,929; 3,362,930; 3,829,292; 3,901,849; 3,910,918; 3,939,164; Published Patent Application Nos. B402,162 and B571,638; British Patent No. 999,806; and an article in the J. Amer. Chem. Soc., Vol. 60 (1938) at page 1458 et seq.